Advanced Electronic Signature AdES

There are four, listed in Article 26 of the eIDAS Regulation. The signature must be uniquely linked to the signatory. It must be capable of identifying the signatory. It must be created using signature creation data that the signatory can use under their sole control, in the regulation's words "with a high level of confidence". It must be linked to the signed data so that any subsequent change is detectable.

The article names no technology. In practice the four requirements are met with a digital signature: a private key that only the signer can use, and a certificate that connects the matching public key to the signer's name. A typed name or a pasted image of a signature does not meet them on its own, because nothing links it to one person or reveals a later edit.

It is admissible as evidence, and it cannot be denied legal effect merely because it is electronic or because it is not qualified. That is the rule in Article 25(1), and it covers every electronic signature. The regulation gives the advanced level no legal effect of its own beyond that.

Equivalence with a handwritten signature is reserved for qualified signatures (Article 25(2)). An advanced signature also carries no presumption in eIDAS. If it is challenged, the party relying on it should expect to show how each of the four requirements was met. National rules on the form of a document are untouched either way (Article 2(3)).

A qualified signature is an advanced signature with two additions: it is created by a qualified signature creation device, and it is based on a qualified certificate (Article 3(12)). Everything in Article 26 applies to both.

The additions change who stands behind the signer's identity. Article 26 says the signature must be capable of identifying the signer, but it does not say who checks that identity or how. That leaves room for very different identity checks behind signatures that are all described as advanced. A qualified certificate, by contrast, is issued only after a qualified trust service provider has verified the person's identity under Article 24(1), and that provider is itself audited and supervised.

The three levels are set side by side in the table under qualified electronic signature.

When no law prescribes a form for the document and the parties are comfortable with the evidence the signature would give them in a dispute. eIDAS leaves questions of form to national and EU law (Article 2(3)), so the first step is always to check whether the document type has a form requirement in the country concerned.

Where it has none, the choice is about proof. The useful test is to picture the signature being denied a year later and ask what the firm could produce: who issued the certificate, how the signer was identified, and where the key was held. If the answers are thin, the label advanced adds little.

Public bodies are a separate case. A member state that requires an advanced signature for an online public service must accept advanced and qualified signatures in the formats set by the Commission (Article 27(1)).

By examining the evidence, because no official register will tell you. Trusted lists record qualified trust service providers and their qualified services (Article 22(1)). Advanced signatures from non-qualified providers do not appear there.

A validation tool such as the European Commission signature validator will show the certificate inside a signed file, its issuer, and whether the document has changed since signing. What it cannot show is how the issuer identified the signer. That has to come from the provider's own documentation.

Common standards may narrow the gap. Article 26(2), added in 2024, lets the Commission adopt reference standards for advanced signatures, following an assessment that was due by 21 May 2026. A signature that complies with standards adopted in that way is presumed to meet the requirements of Article 26.